The present invention relates generally to the treatment of volume deficiency disorders and syndromes, and more particularly to devices that deliver fluid at a controlled pressure into an interstice of a patient to effect tissue expansion and growth of the surrounding tissue, and to surgical procedures for augmenting volumetrically deficient natural body structures or for reconstructing damaged natural body tissue by attachment of tissue segments cultivated by tissue expansion. Methods of delivering fluid at a controlled pressure into an interstice are also disclosed.
Biological volume deficiencies, such as short gut syndrome, are persistent conditions that result when the volumetric capacity of a natural body structure, such as a bladder or a lung, is insufficient to allow the organ to operate effectively or at all. Additionally, the lack of volumetric capacity can create internal fluid pressures or body fluid reflux that damages other organs and tissue. Among the many causes of such deficiencies are birth defects and abdominal trauma.
Presently, the afflicted population receives surgical treatment, typically in the form of augmentation procedures that increase volumetric capacity of the body structure by rebuilding the structure in a procedure that attaches a flap of additional tissue to the afflicted structure. For example, an infant born with insufficient bladder capacity can receive a bladder augmentation in a procedure that typically rebuilds the infant""s bladder by attaching a flap of gastrointestinal tissue to the bladder wall. The surgeon attaches the gastrointestinal tissue to the bladder wall in a manner that increases the surface area of the surrounding wall and thereby increase the volumetric capacity of the bladder. Generally, the surgeon selects gastrointestinal tissue because this tissue normally is available in sufficient amounts within the patient to provide the needed tissue for the augmentation procedure.
Although these procedures can be successful at relieving volumetric capacity deficiency, the complications that arise from attaching different tissue types can be severe and persistent. For example, with respect to bladder augmentation by attachment of gastrointestinal tract, the resulting complications for any patient can include lithiasis, metabolic complications, increased mucous production, increased infections, perforations and even malignant growths within the treated body structure. It is generally understood by the medical community that these complications can arise due to the attachment of a tissue type that lacks sufficient compatibility with the natural tissue of the body structure. Furthermore, bladder augmentation requires invasive surgical procedures which can cause patient discomfort and may require extended times for recovery.
The present invention provides systems and methods for promoting the growth or expansion of biological tissue, thereby increasing the volumetric capacity of a natural body structure. Tissue portions (e.g., which have been surgically resected from the expanded body structure) can also be used in reconstructive surgery. In particular, the present invention provides methods for promoting progressive tissue growth for bladder expansion. To this end, the present invention discloses systems and methods that introduce a pressurized fluid within a body structure, such as a urinary bladder, of a patient. The pressurized fluid causes the surrounding tissue to expand and thereby creates a condition that is generally understood to promote tissue growth. The expansion of the body structure can substantially relieve the condition of volume deficiency.
As used herein, the term xe2x80x9ctissue expansionxe2x80x9d is intended to encompass dilation of natural body lumens, stretching of tissue segments and promotion of new tissue growth in response to an applied pressure. The term xe2x80x9cvolume deficiencyxe2x80x9d is intended to encompass disorder and syndromes related to deficient volumetric capacity of a space or gap between tissue or within a natural body structure and includes by way of example, short gut syndrome and bladder volume insufficiency.
xe2x80x9cInterstitial cavity,xe2x80x9d as the term is used herein, encompasses interstices in a tissue or structure of a natural body structure, spaces and gaps existing between layers of tissue or existing within organs, and can include interstices within the interior of the ureter, bladder, intestines, stomach, esophagus, trachea, lung, blood vessel or other organ or body cavity, and will be further understood to include any surgically created interstice that defines an interior cavity surrounded by tissue.
The term xe2x80x9cinjection port,xe2x80x9d as used herein, refers to an element adapted for introduction of a fluid under pressure. Preferably, an injection port is adapted for pressure-tight connection to a catheter and provides a pressure-tight connection to a source of fluid under pressure. Injection ports suitable for use in the systems and methods of the invention are known in the art and include, but are not limited to, septa (which can be self-sealing), adapters such as threaded nipples or Luer-type adapters, and the like.
In one aspect, the present invention encompasses devices for delivering fluids under pressure to an interstitial cavity (e.g., the urinary bladder) within a patient. Generally, the devices include an inflatable balloon, a catheter element that couples a source of fluid under pressure into fluid communication with the inflatable balloon, and a valve element that is adapted to restrict the flow of the fluid to a select direction of flow and thereby prevent back flow of fluid. The balloon is preferably dimensioned for placement within an interstitial cavity, e.g., the balloon is selected such that the balloon will exert pressure on a tissue wall such that tissue expansion is promoted. The catheter element includes a first lumen for flowing the fluid under pressure into the balloon. The catheter preferably includes at least one drain opening at or near a distal end of the catheter, drainage means (e.g., a body fluid collection element such as a drainage bag) secured to a proximal end of the catheter, and a second catheter lumen in fluid communication with the drain opening and the drainage means, for drainage of a body fluid from the body cavity to the drainage means. Although in a preferred embodiment a single catheter is preferred (which catheter can include a plurality of lumens), it will be understood that the invention also contemplates the use of a plurality of catheter elements (e.g., each catheter having a single lumen) for providing a fluid under pressure and providing a drainage path for a body fluid.
In a preferred embodiment of the invention, the fluid delivering devices further include a pressure release element that reduces fluid pressure within the interstitial cavity by releasing fluid responsive to a user-selected fluid pressure limit. One realization of the pressure release element can be as a release port element that is arranged in fluid communication with the first lumen of the catheter element, and therefore, the fluid within the first catheter lumen, and that further includes a release plug that fluidicly seals the release port to maintain fluid in the first catheter lumen as long as the fluid pressure is below a predefined threshold pressure, and that is adapted to disengage from the release port responsive to the fluid in the first catheter lumen, or in the balloon or interstitial cavity, reaching the threshold fluid pressure limit.
In a particularly preferred embodiment, the fluid delivering devices of the invention can be configured for indwelling placement in a patient""s body. For example, the catheter element of a device of the invention can be dimensionally adapted for indwelling placement within the urethra and bladder of the patient, such that the balloon, when expanded, substantially fills the patient""s bladder. The catheter element can include a drain opening near the distal end portion of the catheter, for draining urine from the bladder. The urine thus drained from the bladder can be flowed through a second catheter lumen to a urine collection element, such as a bag, which can be disposed outside the patient""s body for ready collection and disposal of the urine.
The catheter element is adapted for conveying fluid under pressure to the balloon. The catheter element can include a silastic catheter tube that has a portion dimensionally adapted to fit within an interstitial lumen, such as the ureter. Depending upon the application, the catheter can be a short or long section of, e.g., silastic tube or other polymeric tubing, that extends from an injection port and has the valve element incorporated therein. The catheter element is preferably sized to permit insertion and placement of the catheter (and the attached balloon), into the urethra and bladder,. through a standard cystoscope.
The catheter can connect to a port element that can include an injection port that has an elastic septum adapted for maintaining a fluid under pressure within the catheter element. The port can connect to a pump element that provides a source of fluid at a selected pressure.
In another embodiment, the present invention can be realized as a fluid delivery system that a catheter element for conveying the fluid to the interior of the cavity, a balloon secured to a distal end of the catheter, an injection port element secured to a proximal end of the catheter element that fluidicly couples the pump element with the catheter element, and a valve element that restricts the direction of fluid flow thereby preventing a back flow of pressurized fluid escaping through the injection port. The catheter element includes a first lumen for flowing a fluid under pressure into the balloon. The catheter preferably includes at least one drain opening at or near a distal end of the catheter, a body fluid collection element secured to a proximal end of the catheter, and a second lumen in fluid communication with the drain opening and the fluid collection element, for drainage of a body fluid from an interstitial cavity to a drainage device at a proximal end of the catheter. The apparatus can further include a pump element for providing a source of fluid under pressure.
In one embodiment, the pump element can comprise a syringe element that has a reservoir of fluid in fluid communication with a pressure sensor element, such as a manometer element, to indicate the pressure of fluid being introduced into the balloon. The hollow needle of the syringe element can penetrate the septum, and the septum can elastically form a pressure resistant fluid-tight seal around the penetrating needle. By action of the syringe piston, the fluid in the syringe reservoir is placed under sufficient pressure to introduce fluid into the catheter element and thereby into the balloon in the interstitial cavity. The pressure sensor in fluid communication with the fluid reservoir responds to the pressure of the fluid introduced into the catheter and thereby provides a report of the fluid pressure introduced into the balloon. Thus, the pump element can be adapted to allow the selective control of the fluid pressure provided to the balloon, and thereby control the pressure exerted by the balloon upon the tissue wall of the body cavity in which the balloon is situated.
In another embodiment, the pump element can include a motorized pump element, a fluid reservoir and a control element that includes a manometer or other pressure sensor in fluid communication with the fluid within the catheter element and a control circuit that responds to the measured fluid pressure to controllably operate the pump to maintain the proper fluid pressure within the balloon. In a further embodiment, the control element can include a processing unit that operates the motor pump to vary selectively over time the fluid pressure within the balloon. Preferably, the pump element has a mounting element for removably and replaceably mounting to the injection port element for selectively forming fluid communication with the catheter element.
The injection port element is adapted for fluidicly coupling the pump element to the catheter element and can be integrally formed with the valve that is adapted to prevent pressurized fluid within the catheter from back flowing and escaping through the injection port element. The injection port can have a mounting element that is adapted for removably and replacably coupling in fluid communication to the pump element. The mounting element can be a threaded nipple, a latch or any other coupling that can form a pressure resistant fluid seal. In one embodiment, the injection port element can be an injection port that is adapted for subcutaneous implantation within a patient or for transcutaneous attachment to a patient.
The balloon can be secured to a distal end of the catheter element by a variety of means, some of which are known in the art. The balloon and catheter may be formed integrally or unitarily, or may be bonded together. The balloon, in an uninflated or collapsed state, can be positioned substantially surrounding the outer surface of the catheter element, as is conventional for balloon catheters. Alternatively, the uninflated or collapsed balloon can be positioned within a recess at the distal end of the catheter. The balloon can be inflated in response to a supply of fluid under pressure through the first catheter lumen, and in an inflated state extends outwardly from the recess in the catheter end to fill the body cavity. In the collapsed condition, the balloon can be dimensionally adapted for fitting within the body cavity to be dilated, and in the inflated condition can be dimensionally adapted to volumetrically substantially fill the body cavity and thereby forcibly cause the tissue wall surrounding the cavity to stretch or expand. Additionally, the balloon element can be dimensionally adapted to extend into the interstitial cavity a select distance and thereby contact, in the inflated condition, only a portion of the interstitial cavity to promote tissue expansion in a select section of the surrounding tissue wall. The balloon surface can further include vertical ridges or channels or protrusions that facilitate drainage of body fluids from the body cavity undergoing expansion.
Fabrication of inflatable balloons is well known in the art. The balloon element is preferably adapted to contain the fluid and thereby prevent fluid from entering the body cavity being dilated. The catheter and balloon may be fabricated using a bactericidal-containing synthetic resin, coated with bactericidal or friction-reducing agents, or the balloon may be inflated with a bactericide-treated fluid. In certain embodiments, the fluid is a saline solution, and preferably contains an antibacterial agent. In certain preferred embodiments, the fluid can be a gas, such as compressed air or an inert gas such as nitrogen.
The device can additionally include a pressure release element that reduces fluid pressure by releasing fluid from within the balloon or first catheter lumen. The pressure release element can include a valve and pressure sensor disposed within the pump element, to measure the fluid pressure of the fluid provided to the first catheter lumen and to deactivate the pumping element in response to a fluid pressure within the catheter when the pressure exceeds a selected maximum pressure or to release fluid from within the catheter by action of the valve element.
In another aspect of the invention, methods are disclosed for treating volume deficiency disorders of a body structure by expanding, enlarging, or inflating a volumetrically deficient body structure. The methods employ a tissue dilation system that comprises a source of fluid under a select pressure, an inflatable balloon, a catheter element for carrying the fluid under pressure to the balloon, and a valve element for restricting said fluid under pressure to a select direction of fluid flow. The method further includes the steps of introducing the inflatable balloon into the volume deficient body structure and introducing fluid into the balloon to dilate a tissue wall of the body structure to cause tissue expansion (e.g., by promoting tissue growth), such that the volume deficiency disorder is treated, i.e., the volume of the body structure is increased.
In a preferred practice, the method also includes the steps of monitoring the fluid pressure within the interstitial cavity, and releasing fluid from the interstitial cavity responsive to a select pressure level, to reduce the fluid pressure within the interstitial cavity.
In a further preferred practice of the invention, fluid under pressure is introduced into an interstitial cavity during select intervals, such as by daily or weekly introductions, to promote progressive tissue growth over a selected period of treatment. In one practice, saline fluid, preferably including an antibacterial agent, can be introduced daily into a balloon disposed within a body cavity (e.g., a bladder) and thereby promote tissue expansion and growth thereof. The daily fluid introduction can be maintained for a period of thirty days or, more preferably, until the tissue wall has expanded sufficiently to alleviate a volume deficiency disorder. Alternatively, the fluid pressure within the balloon can be monitored, preferably in connection with a control element on the pump. The control element can operate the pump to maintain a selected pressure within the balloon.
In one practice of the invention, the step of preparing a portion of an interstitial cavity includes selecting an interstitial cavity that has a wall of tissue phenotypically compatible with the volumetrically deficient cavity.
The term xe2x80x9cphenotypically compatible tissuexe2x80x9d as used herein, encompasses tissues that have similar tissue phenotype, similar gross cellular characteristics, can be similarly differentiated, histologically similar, such as having compatible epithelial linings, or derived from the same or similar embryonic structures.
In another aspect of the present invention, methods are provided for expanding tissue to promote tissue growth. The method includes the step of introducing fluid under a select pressure into a balloon disposed within an interstitial cavity by providing a pump element for providing fluid at a select pressure, fluidicly coupling a catheter element between the pump element and the balloon, providing a valve element within the catheter that prevents flow back by restricting the introduction of fluid to a select direction of fluid flow, and sealing fluid-wise the balloon to the catheter element.